Improvement in manufacture of paper-pulp



UNITED STATES PATENT OFFICE.

EBENEZER OLEMO, OF TORONTO, CANADA.

IMPROVEMENT IN MANUFACTURE OF PAPER-PULP.

Specification forming part of Letters Patent No. 29,059, dated July 10,1860.

To all whom it may concern Be it known that I, EBENEZER CLEMO, of thecity of Toronto, in the united counties of York and Peel, and Provinceof Canada, have invented a new and Improved Process of ManufacturingPulp for Paper from Straw or Grasses; and I do hereby declare that thefollowing is a full, clear, and exact description thereof.

My invention consists in the employment, in the manner hereinafterdescribed, of nitric or nitrous acid, or the aqua fortis of commerce, inthe conversion of straw and grasses into pulp for the manufacture ofpaper. By the use of either of these agents I bring the stock to acondition to be reduced to pulp by the action of the beating-engineordinarily employed in the manufacture of paper-pulp.

My invention further consists in the use, in

connection with the described treatment ofthestock with nitric ornitrous acid or aqua fortis, of a subsequent treatment with asolution ofa hydrate or carbonate of an alkali for the purpose of reducing thestock to a fine fibrous pulp without subjectingit to the heating or togive the most satisfactory result, although almost any proportions maybe employed by a due regulation of the temperature employed in theprocess of digestion, a weaker liquor requiring a higher temperature anda stronger liquor being effective at a lower temperature. The processperformed with the diluted acid is conducted as follows: I cut the straor grasses into fine pieces (ifstraw,to about an inch in length) andplace them in a vessel or vessels of earthenware, stoneware, or anymaterial capable of resisting the action of nitric or nitrous acid, andof any convenient form. I then add a sufficient quantity of the dilutedacid to cover the straw or grasses completely, and submit the vessel orvessels, with their contents, to a gentle heat for about four (4) hours.For the strength of acid above specified the heat should be about 200Fahrenheit. At the expiration of the time above specified I remove thestraw or grasses from the vessel or vessels and express the liquor from1t and wash out the acid remaining in it, when it is sufficientlysoftened to be readily converted into pulp by the ordinarybeating-engines, or by the treatment with an alkaline hydrate or carbonate, as hereinafter explained. The acid liquor expressed from the stocksis preserved, to be employed again ,with the addition of a furtherquantity of acid, and its use may be repeated till it becomes too muchloaded with vegetable matters for further use.

The treatment with alkaline hydrate or carbonate to reduce the stockwhich has been softened by the use of nitric or nitrous acid to thestate of pulp suitable for making all ordinary kinds of paper simplyconsists in boiling it, after its removal from the acid liquor, in aweak solution of the hydrate or carbonate of either of the alkalies forabout two hours. The proportion of alkali may be about from one hundred(100) to one hundred and fifty (150) pounds to the ton of pulp, and thequantity of water merely what is sufficient to make the pulp of ordinaryconsistency. The pulp thus obtained, after being washed, will be readyfor bleaching, and whether it is Obtained in this way, or by beating itin an engine after its .being digested in the acid, may be bleached bythe modes commonly adopted for bleaching paper-pulp.

The vessel in which the straw or grasses is digested in the diluted acidmay be closed at the top and furnished with a condensing-pipe passingthrough water to a stoneware condenser. In this condensing-pipe, by theadmission of atmospheric air and steam, I propose to con.- vert thenitric oxide or deutoxide of nitrogen resulting from the decompositionof the acid again into nitric acid, which is condensed in the pipe andcollected in the condenser, to be employed again, as before. In the useof the acid in its concentrated state Iemploy no artificial heat to aidthe process. The straw or grasses havingbeen cut up, as beforedescribed, is steeped in the acid in a suitable vessel for about fourhours, and afterward removed and subjected to a heavy pressure torecover the principal part of the undecomposed portion of the acid,which may be used over and over again on fresh stock till too muchdecomposed,

weakened, or charged with vegetable matter for further service. Thestock, having been thus subjected to the action of the acid, requires tobe washed in a small quantity of water and again submitted to pressureto express the acid liquor, which may be concentrated by evaporation,tobe used again, as before, or for any other use. The acid liquor, havingbeen expressed after washing the softened stock, is ready for furthertreatment either .by the beating-engines or by the alkaline hydrates orcarbonates,

as already described with regard to the stock which has been treatedwith dilute acid.

The following are some of the substances on which I have instituted aseries of experi ments,

